Posts Tagged: Mediterranean fruit fly
The Mediterranean fruit fly, considered the world's worst agricultural pest, is one of at least five fruit flies established in California. It cannot be eradicated.
So says entomologist James Carey of the UC Davis Department of Entomology and Nematology, who has been dogging medflies since his faculty appointment in 1980. (See what drove him.)
Carey and UC Davis-affiliated colleagues Nikos Papadopoulos and Richard Plant wrote the eye-opening research piece, "From Trickle to Flood: The Large Scale, Cryptic Invasion of California by Tropical Fruit Flies" in the current edition of the renowned Proceedings of the Royal Society B.
Their work "clearly demonstrates that at least five and as many as nine species of tropical fruit flies, including the infamous Medfly, are permanently established in California and inexorably spreading, despite more than 30 years of intervention and nearly 300 state-sponsored eradication programs aimed at the flies," wrote Pat Bailey in a UC Davis News Service story released today.
The findings, Bailey pointed out, have "significant implications for how government agencies develop policies to successfully manage pests that pose a threat to California's $43.5 billion agricultural industry."
Carey, an international authority on fruit-fly invasion biology, told her that "Despite due diligence, quick responses, and massive expenditures to prevent entry and establishment of these insects, virtually all of the fruit-fly species targeted by eradication projects have been reappearing in the same locations — several of them annually — and gradually spreading in the state."
Carey, Papadopoulos and Plant detailed the problem in the opening paragraph of their meticulously researched paper: "Since 1954 when the first tropical tephritid fruitfly was detected in California, a total of 17 species in four genera and 11,386 individuals (adults/larvae) have been detected in the state at more than 3348 locations in 330 cities." That's three out of four California cities.
Michael Parrella, professor and chair of the UC Davis Department of Entomology and Nematology: "The study has dramatic implications for California agriculture and the state’s international trading partners, and speaks to the urgent need to alter current eradication policies aimed at invasive species."
Frank Zalom, UC Davis entomology professor and incoming president of the 6500-member Entomological Society of America: “This study deserves serious consideration, and I hope that it helps lead to new discussions on a long-term approach for dealing with fruit flies and similar exotic pests by the United States and international regulatory authorities."
Former UC Davis chancellor Ted Hullar (1987-1994), one of the first to believe in "the science" that Carey presented, said: “From our first conversation, Jim struck me as a serious-minded guy, with strong ideas and clear focus, pursuing his insights and beliefs no matter the struggle. Good science and progress comes from that, making new paths in tough terrain, believing in the power of journey, as well as goal.”
The Medfly prefers such thin-skinned hosts as peach, nectarine, apricot, avocado, grapefruit, orange, and cherry. The female may lay one to 10 eggs per fruit or as many as 22 eggs per day. She may lay up to 800 eggs during her lifetime, but usually about 300.
We remember when the Medfly wreaked economic havoc in the Solano County city of Dixon in September 2007. We were there.
At the time, Carey told us that "this may be just one of many isolated pockets of medfly infestations in California. This is really serious because the invasion process is so insidious."
The Medfly has been multiplying and spreading undetected--like cancer--for years, he said. "It may be a symptom of a much larger problem. But any way you look at it, this is the first really big outbreak in the Central Valley."
CDFA set up a command center at the Dixon May Fair and imposed a 114-mile radius quarantine of fruits, vegetables and nuts. Dixon was deep in the throes of tomato and walnut harvesting. The owner of a 65-acre organic produce farm that ships to 800 clients worried that he might lose $10,000 a week in potential sales.
Among the actions that the California Department of Food and Agriculture (CDFA) took at the onset:
- Stripped all fruit from trees within a 100-meter radius of all Medfly finds
- Ground-sprayed the organic compound Naturalyte (the active ingredient is Spinosad, a naturally occurring product of a soil bacteria) within a 200-meter radius of all Medfly finds
- Set 1,700 fruit fly traps within an 81-square mile grid in all of Dixon and the surrounding area from near the Yolo County border to Midway Road
- Began aerially releasing 1.5 million sterile male medflies (dyed pink for easy detection) over a 12-square mile area on Sept. 14, with weekly releases of 3 million medflies scheduled for at least nine months
- Set up a yearlong command center, with four portable buildings and a task force of 25, on the Dixon May Fair grounds
Fast forward to today. Now that the Medfly has been declared a "permanent resident," what's next?
Carey agrees that “CDFA needs to continue to respond to outbreaks as they occur, but he advocates long-term planning based on “the science” that the insects are established. This includes heightened monitoring levels for the agriculturally rich Central Valley, an economic impact study, risk management/crop insurance, cropping strategies, fly fee zones/post harvest treatments, emergency/crisis planning, genetic analysis and a National Fruit Fly Program.
“Inasmuch as the Mediterranean, Mexican, Oriental, melon, guava and peach fruit flies have all been detected in the Central Valley, monitoring this incredibly important agricultural region should be increased by 5 to 10-fold in order to intervene and suppress populations and thus slow the spread,” Carey says.
“These pests cannot be wished away or legislated out of existence. Policymakers need to come to grips with this sobering reality of multiple species permanently established in our state in order to come up with a long-term, science-based policy for protecting agriculture in our state.”
(See James Carey's website for links to his work on fruit fly invasion.)
Mediterranean Fruit Fly. (Photo by Jack Kelly Clark)
Professor James R. Carey of the UC Davis Department of Entomology will tell you why.
He will discuss the invasion of tropical fruit flies in California at his seminar from 12:05 to 1 p.m., Wednesday, April 3 in Room 1022 of the Life Sciences Addition, corner of Hutchison and Kleiber Hall drives.
Carey's seminar, titled "From Trickle to Flood: The Large-Scale, Cryptic Invasion of California by Tropical Fruit Flies," is the first in the department's spring-quarter seminar series. It's open to all interested persons, and it will be recorded and available for later viewing on UCTV.
"Despite aggressive and costly efforts by government agencies to prevent their introduction, establishment and spread, California has experienced an inexorable march of tropical fruit flies (Tephritidae) into the state with three-fold more species detected and thousands more flies captured than in all other mainland U.S. states combined," Carey says.
"Since 1954 when the first fly was detected a total of 17 species in 4 genera and 11,386 individuals (adults/larvae) have been detected at over 3,348 locations in 330 cities. My colleagues and I conclude from spatial mapping analyses of historical capture patterns and modeling that, despite the approximately 250 emergency eradication projects that have been directed against these pests by state and federal agencies, a minimum of 5 and as many as 9 or more tephritids are established and widespread. This list includes three of the most economically-important species in the world—the Mediterranean, Mexican and oriental fruit flies."
In his seminar, Carey will "outline and discuss the evidence for our conclusions with particular attention to the incremental, chronic, and insidious nature of the invasion involving ultra-small, barely-detectable populations. I will consider the more general implications of our results in scientific, economic, and operational contexts of invasion biology, as well as ethical issues concerned with the purposeful obfuscation of historical fruit fly detection data at individual, administrative and institutional levels."
Carey, former vice chair of the Department of Entomology, focuses his research on insect demography, mortality dynamics, and insect invasion biology. He received his bachelor and master of science degrees from Iowa State University (1973; 1975) and his doctorate in entomology from UC Berkeley (1980).
Highly recognized, he is a fellow of the American Association for the Advancement of Science, the Gerontological Society of America, the California Academy of Sciences, and the Entomological Society of America.
Carey is a noted authority on the invasion of the tropical fruit flies. He served on the California Department of Food and Agriculture's Medfly Scientific Advisory Panel from 1987-1994, testified to the California Legislature "Committee of the Whole" in 1990 on the Medfly Crisis in California, and authored the paper "Establishment of the Mediterranean Fruit Fly in California" (1992, Science 258, 457).
Mediterranean Fruit Fly. (Photo by Jack Kelly Clark)
“The war is over—again,” wrote reporter Pat Brennan of the Orange County Register in a news article published Aug. 14.
Brennan was referring to the war against the Mediterranean fruit fly, a tiny pest that targets some 260 crops. The pest, first detected inCaliforniain 1975, prefers such hosts as peach, nectarine, apricot, avocado, grapefruit, orange and cherry. It is considered the world's worst agricultural pest.
California State Department of Agriculture had earlier announced the eradication of the medfly in three counties:Los Angeles, Solano andSanta Clara.If it were to become permanently established in California, the medflycould cost the state $1.3 to $1.8 billion in annual losses, estimated CDFA Secretary A. G. Kawamura.
I remember whenSolanoCountyag officials discovered four live medflies in a single trap in downtownDixon. The date: Monday, Sept. 10, 2007. Newspapers bannered the story. A quarantine ensued. Farmers fretted, and rightfully so. Later I attended a press conference at theNutTreeAirport, Vacaville;a pilot had just released the first of many millions of sterile male fruit flies over Dixon. He showed us the sterile medflies, dyed pink.
The sterile flies mate with wild flies and biologically force wild populations out of existence, the CDFA says.
UC Davis entomologist James Carey, who has published widely on the medfly, said the pest has been multiplying and spreading undetected--like cancer--for years in California. He says it’s never been really eliminated and he questions whether it could ever be eradicated.
CDFA and Solano County ag officials said no; that an errant tourist likely brought it to Dixon on a piece of fruit fromHawaii. The medfly lays its eggs inside fruit.
Medfly wars ensued.
Carey shared an email he sent Aug .14 to Brennan:
“The absence of medfly appearances anywhere else in the continental U.S. besides California over the past two decades strongly supports the argument that the medfly has never been completely eradicated in our state. CDFA's efforts at eradication have been successful at driving the populations back to subdetection levels for a few years. However, the reappearances of the medfly in the same cities and even in the same locations within these cities is due to a long-term established population. Although I fully acknowledge the need to respond to the medfly when it appears in the state as it did last year, I have no reason to believe that this program will have been any more successful than the previous ones which merely suppressed rather than eliminated the medfly population from the state."
“This recent declaration of eradication is around the 50th emergency response to medfly outbreaks over the past two decades by CDFA, virtually all of which have been in the same general locations. To my knowledge during this same period no other state such as Arizona, Florida or Texas has experienced any outbreaks even though these states, like California, have climates suitable for the medfly establishment and have many tourists and migrants who are capable of introducing the medfly. These states have experienced no outbreaks while California has experienced 50.”
The CDFA Web site says medflies are not established in California.
"These (medflies) and other exotic pests have not become established in California due to (1) strict federal exterior and state interior quarantines, (2) a pest detection program, and (3) aggressive eradication programs when an infestation is discovered."
Carey, who has plotted all medfly finds in California, says medfly populations “do not really get going until late summer and fall. Stay tuned for this fall.”
One thing is certain: the little bugger draws a lot of attention. That’s because, as Brennan wrote, it “attacks so many crops.”
Mediterranean fruit fly